Some mobile information apparatuses have multiple screens. A mobile phone is representative of this kind of mobile information apparatus (see Patent Literature 1). As more complex functions and a larger-sized contents are realized, mobile phones are required to have a capability of displaying more information. In order to satisfy such a demand, a multi-screen mobile phone having multiple screens is being examined, in addition to a higher resolution and a larger screen. As one method for using a multi-screen mobile phone, it plausible for a user o view different screens by switching his line of sight from one screen to another screen from among multiple arrayed screens on the mobile information apparatus.
In a mobile information apparatus having multiple screens, however, power consumed by the display sections generally increases in proportion to the number of the display sections. Therefore, it is difficult to realize low power consumption in a mobile information apparatus having multiple screens, and therefore, it is difficult to operate it by a battery for a long time.
To cope with this problem, there is proposed a technique for controlling display of multiple screens according to the state of the mobile information apparatus (see Patent Literatures 1 to 3).
Patent Literature 1 discloses, as a fifth exemplary embodiment, a technique for controlling the brightness of the screens provided for a body and a lid part, respectively, according to the folding angle formed by the body and the lid part, the body and the lid part being openably and closably connected with each other such that their screens face each other when they are closed.
Patent Literature 2 discloses, as a fourth exemplary embodiment, a mobile phone having two cases on the body part side and the lid part side, respectively, which are openably and closably connected with each other, the case on the lid part side being provided with a main LCD to be used in an open state and the case on the body side being provided with a sub LCD mainly to be used mainly in a closed state. The mobile phone switches on and off the light of the main LCD and the light of the sub LCD on and off according to the direction in which it is placed and the open/closed state.
Patent Literature 3 discloses a technique in which a mobile terminal apparatus is provided with displays on the front side and back side of a case, respectively, and is also provided with a gravity sensor that controls on/off of the front-side display and the back-side display according to an angle of the case obtained by the gravity sensor.
There is also proposed a technique in which it is determined whether or not a user is looking at a display or not, from image data obtained by a camera, and the brightness of the display is decreased when the user is not looking at the display (see Patent Literature 4).
A mobile terminal apparatus described in Patent Document 4 is not provided with multiple displays but is provided with one display, and it is further provided with a camera. The mobile terminal apparatus determines whether or not the user is looking at the display or not by processing image data obtained by the camera. When the user is not looking at the display, the mobile terminal apparatus decreases the brightness of the display.